Does not heat up when i use start - LG LCRT2010ST Microwave Oven

control board is bad.

I would suspect a door switch or door switch mount.

See my help file on door switches here:
http://031d26d.namesecurehost.com/mwc/doorsw.txt

select power 100 to heat things,

You can use to set the timing in order of the heat required. Also using the grade rating of the heating coupled with the time set, the food can be easily heated without burning.
To start with use low heat and long time, the try with medium heat and lesser time and then choose high heat and short time. You must be able to use the settings accordingg to your requirement.
Hope this advice helps

90% chance that there is a magnetron failure

I have narrowed the problem down to the door, but I have not yet repaired it nor do I know how. If I hold the door after closing, and hit start it will begin the heat process, but when I let go of the door it stops.

HI. your control board has failed. you will need to replace the control board asap if possible.

I have the same problem. Everything seems to work except it doesn't heat up food.
I remember last time when it was working. I pressed the start botton before I closed the door. So it didn't start automatically, and I pushed start and it worked(it still heat up the food), but it doesn't work now. Help Please!!!
I have a Whirlpool Gold GH5184XPQ.

Thanks in advance

if electronic control, one of two things come to mind. 1)your toutch pad is defective.replace it. 2)you electronic board has a leaky component.not very likly though. believe it or not, ive seen it start before by itself then i noticed a large quantity of bugs inside the glass which i realised triggered the microwave 0ff.